Marker Landing Pad Layout for GNSS-Denied Pose Estimation
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Solution Overview
Problem
Existing landing pad designs for vehicles lack a systematic approach to ensure high accuracy and availability of position estimates during the descent and takeoff phases, particularly in scenarios where Global Navigation Satellite System (GNSS) is denied or degraded.
Innovation Solution
A method for designing a marker-based landing pad with symmetrical placement of markers forming convex hulls along the X and Y axes, ensuring maximum visibility and overlap to maintain accurate position estimation throughout the landing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If markers are placed sparsely on the landing pad, then the device complexity is reduced, but the measurement precision of vehicle position and orientation deteriorates
Solution Approach 1:
The marker set is segmented into multiple groups (first group with larger markers, second group with smaller markers) arranged in distinct convex hulls. This segmentation allows the system to use different marker groups at different descent phases, maintaining high measurement precision while managing device complexity through organized structure.
Solution Approach 2:
The patent introduces a hierarchical dimension to marker placement by creating nested convex hulls (first convex hull containing second convex hull). This dimensional organization allows the system to transition between marker groups systematically, improving position estimation accuracy without proportionally increasing overall complexity.
2Measurement precision
If markers are placed to ensure high accuracy position estimation, then the measurement precision improves, but the availability of markers during descent phase deteriorates due to limited visibility
Solution Approach 1:
The system dynamically transitions between different marker groups based on vehicle descent phase. At higher altitudes, the first group of markers in the outer convex hull provides visibility and accuracy. As the vehicle descends, the second group of markers in the inner convex hull becomes more visible and takes over for precise positioning near the landing pad, ensuring continuous marker availability.
Solution Approach 2:
The patent implements nested convex hulls where the second convex hull (formed by second group of markers) is contained within the first convex hull (formed by first group of markers). This nesting ensures that at any descent phase, at least one group of markers remains visible to the vehicle's camera, maintaining both accuracy and availability throughout the landing process.
3Reliability
If multiple groups of markers are arranged to maintain visibility throughout descent, then the reliability of position estimation improves, but the device complexity increases
Solution Approach 1:
The patent employs asymmetric marker group configurations within each convex hull, where markers are not uniformly distributed but strategically positioned to maximize visibility and measurement accuracy at different descent phases. This asymmetric arrangement optimizes reliability without requiring excessive symmetry that would increase complexity.
Solution Approach 2:
Each marker group serves multiple functions: the first group of markers provides initial approach guidance and coarse positioning, while also serving as backup for the second group. The second group provides precise landing positioning and can serve as backup for the first group, creating a universal system where markers have redundant roles, improving reliability without proportionally increasing complexity.
Data Source
AI summary
A method comprises providing a vehicle landing pad with a reference frame origin at a center thereof, and X and Y axes through the reference frame origin; arranging a first group of markers, each having a first size, on the pad such that the first group of markers form a first convex hull about the center of the pad; and arranging a second group of markers, each having a second size less than the first size, on the pad such that the second group of markers form a second convex hull within the first convex hull. The first and second groups of markers are located symmetrically with respect to the center of the pad along the X and Y axes so as to yield a position estimation solution for landing a vehicle having a highest accuracy when compared with placing markers at other locations along the X and Y axes.